Two subspecies have been recognised, namely Homopus signatus signatus and H. s. cafer, with a zone of intergradation in the eastern part of the range in the western Great Karoo (Boycott 1986, 1989; Bour 1988; Iverson 1992; Branch 1998; Boycott and Bourquin 2000; Loehr 2008). However, a range-wide study by Daniels et al. (2010) evaluated the genetic distinctiveness of the two putative subspecies as well as intergrades and found limited differentiation within the species. It was concluded that H. s. cafer is not a valid taxon, rendering H. signatus monotypic. However, the status of a population from the Pofadder area requires further investigation (Daniels et al. 2010). Colour patterns previously used to distinguish the two subspecies appear to be related to crypsis on different substrates.

Justification:
This species is assessed as Vulnerable as it has undergone an inferred population reduction of over 30% in the past three generations (75 years) due to anthropogenic land transformation, where the causes of destruction may not have ceased, based on direct observation [A2a], a decline in AOO, EOO and habitat quality [A2c], and actual levels of exploitation [A2d]. These declines are considered likely to continue into the future.

Endemic to South Africa, occurring mainly along the West Coast region of the Western Cape and Northern Cape, from Piketberg and around Citrusdal in the south, northwards across the Olifants River into the Namaqualand Hardeveld to the Springbok-Steinkopf area. Eastwards, the distribution reaches as far inland as the Klipwerf-Loeriesfontein-Calvinia area of the Roggeveld-Bokkeveld region in the Northern Cape. The most northerly records are from the Richtersveld (Bauer and Branch 2003 [2001]) and from just north of Pofadder (Branch et al. 2007). Griffin (2003) did not substantiate any Homopus signatus records from Namibia, including a record from the Fish River Canyon Park (Boycott and Bourquin 2000). Earlier records of this species from Namibia (Mertens 1955, 1971) are referable to H. solus (Branch 2007).

Occurs predominantly in the winter rainfall region of the northwestern Succulent Karoo and Fynbos biomes along the West Coast and adjacent inland of South Africa. Found from a few metres above sea level on the West Coast to elevations of around 1,000 m in the interior at Loeriesfontein-Calvinia and the Cederberg Range (Boycott 1989). Shows a particular preference for rocky terrain, which includes typical Namaqualand and Hardeveld granite koppies (hills) in the north, and typical Sandveld and Cederberg sandstone koppies and rocky ridges in the south. Occurs in low to medium-high Namaqualand succulent shrubland (blomveld) and heuweltjieveld, and fynbos and strandveld shrub vegetation, both in the Succulent Karoo and Fynbos biomes. Prefers to shelter in rock crevices or under medium to large boulders and rock slabs, a behaviour that provides protection against temperature extremes and predation.

Listed as Restricted by Boycott (1988) and as Lower Risk/near threatened in the 1996 IUCN global listing (IUCN 1996). Currently considered Vulnerable, mainly due to human-induced habitat degradation and destruction and the international reptile pet trade. Observations and focused research throughout the known range indicate that this species is intolerant of habitat modification. There appears to be a strong correlation between population status and habitat quality. Severe habitat fragmentation has resulted from extensive agricultural development throughout the range and especially in the Sandveld region. This includes the irreversible alteration of the inter-koppie (small hill) habitat—a zone that probably plays an important role in inter-population gene flow. Overgrazing by domestic stock, especially goats, further degrades and threatens remaining natural koppie habitats. There is illegal collection for export to the international pet trade, although this is infrequent. Midgley et al. (2005) recorded the imminent threat and potential impact of global climate change on the western parts of South Africa. Loehr (2008) clearly demonstrated that the expected changes in rainfall pattern and temperature across the range is likely to severely impact growth rates and fecundity of individuals, and consequently the survival of the species.

In-Place Research, Monitoring and Planning Action Recovery plan:No Systematic monitoring scheme:NoIn-Place Land/Water Protection and Management Conservation sites identified:Unknown Occur in at least one PA:YesIn-Place Species ManagementIn-Place Education Included in international legislation:Yes Subject to any international management/trade controls:Yes

Bauer, A.M. and Branch, W.R. 2003 [2001]. The herpetofauna of the Richtersveld National Park and the adjacent northern Richtersveld, Northern Cape Province, Republic of South Africa. Herpetological Natural History 8: 111-160.